<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .test{
            width: 120px;
        }
        table{
            border-collapse: collapse;
        }
        thead tr{
            background-color: #0c85d0;
            border-collapse: collapse;
        }
        th{
            text-align: left;
            width: 60px;

        }
    </style>
    <script src="jquery-3.4.1.min.js"></script>
</head>
<body>
<div class="content">
    <table>
        <thead><tr>
            <th>123</th>
            <th class="test">456</th>
            <th>756</th>
        </tr></thead>
        <tbody>
        <tr><td>123</td>
            <td>456</td>
            <td>789</td></tr>
        </tbody>
    </table>
</div>
<script>
    var test={
        a:{
            abc:'1'
        },
        b:''
    }
    var m = test.a;
    test.b=m;
    console.log(test)
</script>
</body>
</html>